Rocket assisted projectile

ABSTRACT

A rocket assisted projectile round consisting of a cartridge, a rocket motor and projectile wherein the cartridge propels the rocket motor out of a firing tube and ignites ignition powder in the rocket motor. Thereafter, the rocket motor is ignited and it propels the projectile in flight.

limited States Patent Nelms et all. Aug. 7, 1973 ROCKET ASSISTED PROJECTILE 2,870,711 1/1959 Barr etal. 244/327 [76] inventors: Joe W. Nelms; William L. Nelms, 2,405,415 8/1946 Ekserglan 102/343 both of Harvest, Ala. 35749 Primary Examiner-Robert F. Stahl [22] F1led: Sept. 23, 1970 Phillips [21] Appl. No.: 74,622

[57] ABSTRACT [52] US. Cl 244/3.24, 102/38, 102/49.7 [51] Int CL 1742b 15/16 A rocket ass1sted pro ectlle round cons1st1ng of a car- [58] Field 93 49 3 tridge, a rocket motor and projectile wherein the car- 24473 3 tridge propels the rocket motor out of a firing tube and I ignites ignition powder in the rocket motor. Thereafter, [56] References Cited the rocket motor is ignited and it propels the projectile UNITED STATES PATENTS 3,176,615 4/1965 Matthew 102/49.7 X 3 Claims, 6 Drawing Figures 40 /48 I m 7 l AIR 52 FLOW GAS I FLOW 4s 50 54 l l l L- l PAIENIH] AU; 71975 FIG. I

FIG. 3

s/As FLOW 56 Joe W. Nelrns William L.Nelms, INVENTORS.

FIG. 6

ROCKET ASSISTED PROJECTILE This invention relates to projectiles and particularly to projectiles which are barrel or tube fired and thereafter are propelled by rocket propulsion.

An object of the present invention is to provide a weapon system which is capable of being operated by one person as a shoulder fired weapon, that has a minimum recoil, and at the same time includes means for achieving high velocities for more accurate trajectories than obtainable with known type systems.

Another object of this invention is to provide an improved rocket assisted projectile round in which the round is cartridge tired from a closed or partially closed breech tube and thereafter a high velocity rocket is ignited to accurately carry the projectile round toward its target.

A still further object of this invention is to provide a rocket assisted projectile round in which the rocket motor of the round is ignited by gases from the cartridge and thrust build-up is accurately timed to occur subsequent to the projectile leaving the barrel from which it is fired.

A still further object of this invention is to provide a rocket assisted projectile round in which the round is propelled at supersonic velocities and spin stabilized earlier in flight than with prior systems for very accurate target acquisition.

A projectile round as contemplated by this invention would be fired from a barrel or tube in which the breech can be either totally closed or partially closed. The round would have three basic sections, an after section consisting of a cartridge adapted to be fired by percussion cap or by electrical squib, a middle section consisting of a rocket motor, and a forward section consisting of the projectile war-head to be propelled. The explosive charge of the cartridge is tubular in shape and includes a conical forward portion which nests within the after end of the rocket nozzle of the intermediately positioned rocket motor. The projectile is then supported by the forward end of the rocket. A plurality of lands, which serve also as rails, extend for substantially the entire length of the rocket motor and provide two functions. First, they function as lands when the projectile is within the firing barrel and permit a predetermined amount of gases to escape forward to keep down breech pressures, and two, when the round has left the tube, the lands function together with a novel configuration of tail fins, which pre-spin the round prior to it leaving the barrel, and prior to rocket motor ignition to stabilize the round in flight. The tail fins include a triangular shaped surface, a rear surface of which reacts with cartridge gases to initiate rotation of the rocket and a forward surface of which reacts with air flow in flight to accelerate and maintain rotation, and thus spin stabilize the rocket and projectile.

These and other objects, features and advantages of the invention will become more apparent from the following description when considered together with the drawings in which:

FIG. 1 is an overall side view, partially in section, of a projectile as contemplated by this invention;

FIG. 2 is a side view of the projectile positioned for firing in a partially opened breech arrangement for recoilless operation.

FIG. 3 is an exploded view of a portion of FIG. 1;

FIG. 4 is an enlarged cross section view taken along the lines 4-4 of FIG. 1;

FIG. 5 is an enlarged section view taken along the lines 55 of FIG. 1; and

FIG. 6 is an enlarged view of a portion of the fin structure of the rocket shown in [FIG. 5.

Referring now to the drawings, projectile round 10 consists of cartridge 12, rocket motor 14 and projectile 16. Round 10 is adaptable to be fired by a partially closed or fully closed firing tube. This is to adjust recoil to essentially zero or provide maximum protection for personnel or equipment to the rear oflauncher. Projectile 16 is merely representative of any type projectile or pay load which would be propelled by round 10. Cartridge 12 includes a standard percussion ignition cap 18 and explosive charge 20 which is encased in a perforated tube 22 which in turn is encased in consummable sleeve 23. The forward portion 24 of perforated tube 22, and thus explosive charge 20, sealed by consummable plug 25 is contained in conical tube 22 and nests within the flared out rear portion 26 of rocket nozzle 28 of rocket motor 14.

Rocket motor 14 consists basically of a solid propellant 30, contained in insulating liner 32, outer motor casing 34, and igniter powder 36 retained in consummable sleeve 37, and nozzle 28. The igniter powder extends from consummable plug 38 into solid propellant a sufficient distance to obtain ignition and proper burning rates.

Rocket nozzle 28 with throat liner 29 is enclosed in a shroud 40 which tapers from the after edge 42 of casing 34 to the after end 44 of nozzle 28. Shroud 40 is conical and provides a stream line contour for the after portion of rocket motor 14.

As a particular feature of this invention, spin stabilization of rocket motor 14 is achieved by the combination of lands or rails 46 extending longitudinally for substantially the full length of casing 34 and fin assemblies 48 (FIGS. 5 and 6) which extend outward from shroud 40 and generally form longitudinally extension of lands 46. As shown, there are four lands 'or rails 46 and four fin assemblies 48.

Each fin assembly 48 consists of an elongated forward fin 50 of uniform thickness and a rear positioned deflector 52, which is triangular in configuration. Deflector 52 has two deflection surfaces, front deflector surface 54 and rear deflector surface 56.

In operation, projectile round 10 would be placed in a barrel or tube 11 for firing with a closed, or partially closed, breech. Ignition cap 18 would be struck by conventional means such as by a firing pin or firing hammer on tube 17, not shown. Explosive charge 20 would be thus ignited and burn. It would burn through perforated tube 22 and consummable sleeve 23 and expanding gases would fill chamber 58. At the same time, the burning gases would ignite igniter powder 36 in nozzle 28. Rocket motor 14 would be propelled forward by the expanding gases in chamber 58 and rapidly accelerate before reaching the end of tube 17, it reaching, for example, a velocity in the tube of 200-400 feet per second. Some of the gases in chamber 58 pass out of the front of the firing tube, flowing in the region between casing 34 and the tube. This is made possible by lands 46 which provide a spaced support for round 10 within tube 17, in addition to providing stabilization during flight as described above. As the gases move forward they apply a force on rear deflector surface 56 of deflector 52 which causes rocket motor 14 to commence rotation and to accelerate in rotation under this force until fin assembly 48 clears the end of the tube. Thereafter, rotation is further accelerated and maintained, and thus stabilization is maintained, by air flow acting against front deflection surface 54. As will be noted, the angle a between front deflection surface 54 and a longitudinal line 60 is small with respect to angle b between rear deflection surface 56 and line 60. This configuration permits maximum initial torque from the high pressure chamber gases to rapidly accelerate rotation while rocket 14 is still in the tube, and thereafter, sufficient torque with minimum drag from air flow while the rocket is air borne.

Igniter powder 36 provides a timed ignition of propellent 30. Typically, the volume and composition of powder 36 would be chosen to assure that ignition of propellent 30, and thus rocket thrust, would commence sufficiently in distance from the launching tube for safety to the person or persons doing the firing, and yet, sufficiently close to assure that there is negligible deviation from desired trajectory between the time the round leaves the tube and rocket ignition. With the configuration shown, stabilization of flight is achieved on the order of 0.1 of a second or less after launch in contrast to 0.3-0.7 of a second typically required for stabilization of known types of rocket assisted projectiles.

While four lands 46 are shown, 3 to 8 or ever more lands may be employed and represent a particular feature of this invention. One, they extend substantially the complete length of rocket motor 14 and serve to give precisely spaced clearance between the round or projectile and wall of launch tube 17 to thus accurately meter escape gases and control gas pressures. Second, the lands provide a minimum of friction during initial spin-up produced by forward gas pressure upon rear deflector surfaces 56. Third, lands 46 provide a method of machining consistently close tolerance clearances between projectile lands and the tube walls of a few thousandths of an inch. The height and width of lands 46 depend somewhat upon the caliber, density of projectile, spin rate and velocity of projectile. Generally, however, the lands would have a ratio of between 1 to 10 and l to 40, preferably between 1 to and l to 40, in terms of land heights to caliber diameter.

While as shown in the drawings, firing of cartridge 12 is accomplished by percussion cap 18, it is to be appreciated that other means of firing, such as by an electrical igniter, may be employed.

By means of the invention thus described, Applicant has provided an improved rocket assisted projectile. It enables launching by light weight tubes with breech pressures as low as 3,000 to 8,000 P.S.l. and yet the projectile is rapidly stabilized for powered, accurate flight. Further, the invention enables burning gases from cartridge 12 to be leaked off around rocket motor 14 and thus minimize gas pressures for minimum recoil, and at the same time, to utilize the escaping gases to apply the initial torque to rocket motor to accelerate spin stabilization. This thus substantially improves accuracy over known types of tube launched rockets. This follows since, typically, spin stabilization is achieved by complex spin up jet systems, by mechanical devices or upon the ignition of the rocket motor and gas pressure applied to reaction vanes. This latter method must be effected sufficiently distant from the launching tube to mimize danger to the operator and surrounding equipment. In practice this means that the projectile will be unpowered and thus coast for some distance, often 50 to 200 ft., and during coast the projectile is particularly sensitive to wind conditions and effects of gravity. As a result the precise position in space of ignition of the rocket motor and the commencement of powered rocket flight becomes unpredictable and thus so does overall accuracy of the system.

It is particularly believed that the invention provides means for providing the best performance characteristics of the tube type artillery weapons and of free flight rocket systems. The invention achieves reduction in weight over known systems by providing a projectile which permits gases to be leaked off in a forward direction or in a rearward direction for essentially zero recoil. It reduces back blasts and this increases range over standard open breech projectile weapons. By achieving earlier spin stabilization, accuracy is increased over standard free flight rockets while at the same time providing a reduction in system recoil.

What is claimed is:

1. A rocket assisted projectile round adapted to be fired from a tube and comprising:

A. a cartridge comprising:

1. a cartridge casing having an elongated cylindrical wall structure which is generally opened at one end to receive the after end of a rocket motor and closed at the other end,

2. an explosive charge concentrically positioned with said casing and supported at one end by the closed end of said casing, said charge being generally spaced from the said elongated cylindrical wall structure ofsaid casing, and a suspended end of said explosive charge extending toward the open end of said cartridge casing,

3. ignition means for igniting said explosive charge;

B. a rocket motor comprising:

1. a cylindrical rocket casing,

2. a propellent charge confined in said rocket casing,

3. a rocket nozzle positioned at the after end of said rocket casing and including:

a. a plurality of elongated fins spaced about the periphery of said rocket nozzle; and

b. spin stabilization means formed at the after end of at least two of said fins, each said spin stabilization means comprising a triangular wedge-shaped deflector extending normal to the surface of a said elongated fin.

4. a plurality of elongated lands of a height of onetenth to one-fortieth of the diameter of the cylindrical rocket cavity extendinglongitudinally for substantially the full length of said rocket casing;

C. mounting means for mounting the after end of said rocket motor within the said open end of said cartridge casing, said explosive charge of said cartridge being positioned proximate to said motor nozzle of said rocket motor for igniting said rocket motor from expanding gases from said explosive charge following the firing of said cartridge; and

D. a projectile supported by said forward end of said rocket motor casing,

whereby expanding gases from said cartridge react with an after surface of a said deflector to initiate rotation of said rocket motor, and thereafter, air flow reacting with the forward surface of said deplosive charge extends into said nozzle and conforms to the flare of said nozzle.

3. A rocket assisted projectile round as set forth in claim 2 wherein said ignition means of said cartridge comprises percussion cap means mounted at said closed end of said cartridge. 

1. A rocket assisted projectile round adapted to be fired from a tube and comprising: A. a cartridge comprising:
 1. a cartridge casing having an elongated cylindrical wall structure which is generally opened at one end to receive the after end of a rocket motor and closed at the other end,
 2. an explosive charge concentrically positioned with said casing and supported at one end by the closed end of said casing, said charge being generally spaced from the said elongated cylindrical wall structure of said casing, and a suspended end of said explosive charge extending toward the open end of said cartridge casing,
 3. ignition means for igniting said explosive charge; B. a rocket motor comprising:
 1. a cylindrical rocket casing,
 2. a propellent charge confined in said rocket casing,
 3. a rocket nozzle positioned at the after end of said rocket casing and including: a. a plurality of elongated fins spaced about the periphery of said rocket nozzle; and b. spin stabilization means formed at the after end of at least two of said fins, each said spin stabilization means comprising a triangular wedge-shaped deflector extending normal to the surface of a said elongated fin.
 4. a plurality of elongated lands of a height of one-tenth to one-fortieth of the diameter of the cylindrical rocket cavity extending longitudinally for substantially the full length of said rocket casing; C. mounting means for mounting the after end of said rocket motor within the said open end of said cartridge casing, said explosive charge of said cartridge being positioned proximate to said motor nozzle of said rocket motor for igniting said rocket motor from expanding gases from said explosive charge following the firing of said cartridge; and D. a projectile supported by said forward end of said rocket motor casing, whereby expanding gases from said cartridge react with an after surface of a said deflector to initiate rotation of said rocket motor, and thereafter, air flow reacting with the forward surface of said deflector accelerates and sustains rotation, and thus spin stabilization during flight, and whereby said round may be initially fired by initiation of said ignition means and propelled for a relatively short distance and thereafter propelled by said rocket motor.
 2. an explosive charge concentrically positioned with said casing and supported at one end by the closed end of said casing, said charge being generally spaced from the said elongated cylindrical wall structure of said casing, and a suspended end of said explosive charge extending toward the open end of said cartridge casing,
 2. a propellent charge confined in said rocket casing,
 2. A rocket assisted projectile round as set forth in claim 1 wherein said rocket nozzle is flared and said explosive charge extends into said nozzle and conforms to the flare of said nozzle.
 3. a rocket nozzle positioned at the after end of said rocket casing and including: a. a plurality of elongated fins spaced about the periphery of said rocket nozzle; and b. spin stabilization means formed at the after end of at least two of said fins, each said spin stabilization means comprising a triangular wedge-shaped deflector extending normal to the surface of a said elongated fin.
 3. ignition means for igniting said explosive charge; B. a rocket motor comprising:
 3. A rocket assisted projectile round as set forth in claim 2 wherein said ignition means of said cartridge comprises percussion cap means mounted at said closed end of said cartridge.
 4. a plurality of elongated lands of a height of one-tenth to one-fortieth of the diameter of the cylindrical rocket cavity extending longitudinally for substantially the full length of said rocket casing; C. mounting means for mounting the after end of said rocket motor within the said open end of said cartridge casing, said explosive charge of said cartridge being positioned proximate to said motor nozzle of said rocket motor for igniting said rocket motor from expanding gases from said explosive charge following the firing of said cartridge; and D. a projectile supported by said forward end of said rocket motor casing, whereby expanding gases from said cartridge react with an after surface of a said deflector to initiate rotation of said rocket motor, and thereafter, air flow reacting with the forward surface of said deflector accelerates and sustains rotation, and thus spin stabilization during flight, and whereby said round may be initially fired by initiation of said ignition means and propelled for a relatively short distance and thereafter propelled by said rocket motor. 